By Josh Perry, Editor
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Researchers from Stanford (Calif.) University and the U.S. Department of Energy (DOE) SLAC National Accelerator Laboratory used a new laser technique to visualize hotspots within lithium-metal batteries and determined that hotspots can lead to the growth of dendrites that could cause short circuits.

The hotter a hotspot inside a battery, the more lithium metal buildup it attracts and the more susceptible the battery becomes to a short circuit.
(SLAC National Accelerator Laboratory)

According to a report from SLAC, the researchers used lasers to create hotspots on electrodes and then used scanning electron microscopes to see that the lithium metal gathered on hotspots faster than other areas of the battery.

“If they grow long enough, these dendrites could puncture the barriers that separate positive and negative sides of batteries, causing short circuits,” the article explained. “Short circuits like these can cause runaway temperatures that might explain why some batteries explode or catch on fire.”

The scientists hope that other researchers will utilize this technique to study batteries and that it will lead to better thermal management solutions and increased battery safety.

The research was recently published in Nature Communications. The abstract stated:

“Fast-charging and high-energy-density batteries pose significant safety concerns due to high rates of heat generation. Understanding how localized high temperatures affect the battery is critical but remains challenging, mainly due to the difficulty of probing battery internal temperature with high spatial resolution.

“Here we introduce a method to induce and sense localized high temperature inside a lithium battery using micro-Raman spectroscopy. We discover that temperature hotspots can induce significant lithium metal growth as compared to the surrounding lower temperature area due to the locally enhanced surface exchange current density.

“More importantly, localized high temperature can be one of the factors to cause battery internal shorting, which further elevates the temperature and increases the risk of thermal runaway.

“This work provides important insights on the effects of heterogeneous temperatures within batteries and aids the development of safer batteries, thermal management schemes, and diagnostic tools.”